Diffuse large B cell lymphoma is the most common type of non-Hodgkin’s lymphoma, representing approximately one-third of all cases and involving the gastrointestinal tract in about 18%. With the development of modern chemotherapeutic regimens and advances in medical care, the prognosis for malignant lymphoma can be excellent. However, because of the aggressive adjuvant therapy required, complications such as bowel perforation may be fatal. In cases of chemotherapy for malignant lymphoma, we should keep in mind the possibility of perforation of the bowel after chemotherapy. Early detection is important to save patients. (J Korean Surg Soc 2009;76:61-65)